<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License.  You may obtain a copy of the License at

	  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
		"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Apache Tomcat WebSocket Examples: Multiplayer Snake</title>
<style type="text/css">
#playground {
	width: 640px;
	height: 480px;
	background-color: #000;
}

#console-container {
	float: left;
	margin-left: 15px;
	width: 300px;
}

#console {
	border: 1px solid #CCCCCC;
	border-right-color: #999999;
	border-bottom-color: #999999;
	height: 480px;
	overflow-y: scroll;
	padding-left: 5px;
	padding-right: 5px;
	width: 100%;
}

#console p {
	padding: 0;
	margin: 0;
}
</style>
<script src="https://cdn.jsdelivr.net/sockjs/0.3.4/sockjs.min.js"></script>
</head>
<body>
	<noscript>
		<h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets rely on Javascript being enabled. Please enable Javascript and reload this page!</h2>
	</noscript>

	<div style="float: left">
		<canvas id="playground" width="640" height="480"></canvas>
	</div>
	<div id="console-container">
		<div id="console"></div>
	</div>
	<script type="text/javascript">
		var Game = {};

		Game.fps = 30;
		Game.socket = null;
		Game.nextFrame = null;
		Game.interval = null;
		Game.direction = 'none';
		Game.gridSize = 10;

		function Snake() {
			this.snakeBody = [];
			this.color = null;
		}

		Snake.prototype.draw = function(context) {
			for ( var id in this.snakeBody) {
				context.fillStyle = this.color;
				context.fillRect(this.snakeBody[id].x, this.snakeBody[id].y,
						Game.gridSize, Game.gridSize);
			}
		};

		Game.initialize = function() {
			this.entities = [];
			canvas = document.getElementById('playground');
			if (!canvas.getContext) {
				Console.log('Error: 2d canvas not supported by this browser.');
				return;
			}
			this.context = canvas.getContext('2d');
			window.addEventListener('keydown', function(e) {
				var code = e.keyCode;
				if (code > 36 && code < 41) {
					switch (code) {
					case 37:
						if (Game.direction != 'east')
							Game.setDirection('west');
						break;
					case 38:
						if (Game.direction != 'south')
							Game.setDirection('north');
						break;
					case 39:
						if (Game.direction != 'west')
							Game.setDirection('east');
						break;
					case 40:
						if (Game.direction != 'north')
							Game.setDirection('south');
						break;
					}
				}
			}, false);
			Game.connect();
		};

		Game.setDirection = function(direction) {
			Game.direction = direction;
			Game.socket.send(direction);
			Console.log('Sent: Direction ' + direction);
		};

		Game.startGameLoop = function() {
			if (window.webkitRequestAnimationFrame) {
				Game.nextFrame = function() {
					webkitRequestAnimationFrame(Game.run);
				};
			} else if (window.mozRequestAnimationFrame) {
				Game.nextFrame = function() {
					mozRequestAnimationFrame(Game.run);
				};
			} else {
				Game.interval = setInterval(Game.run, 1000 / Game.fps);
			}
			if (Game.nextFrame != null) {
				Game.nextFrame();
			}
		};

		Game.stopGameLoop = function() {
			Game.nextFrame = null;
			if (Game.interval != null) {
				clearInterval(Game.interval);
			}
		};

		Game.draw = function() {
			this.context.clearRect(0, 0, 640, 480);
			for ( var id in this.entities) {
				this.entities[id].draw(this.context);
			}
		};

		Game.addSnake = function(id, color) {
			Game.entities[id] = new Snake();
			Game.entities[id].color = color;
		};

		Game.updateSnake = function(id, snakeBody) {
			if (typeof Game.entities[id] != "undefined") {
				Game.entities[id].snakeBody = snakeBody;
			}
		};

		Game.removeSnake = function(id) {
			Game.entities[id] = null;
			// Force GC.
			delete Game.entities[id];
		};

		Game.run = (function() {
			var skipTicks = 1000 / Game.fps, nextGameTick = (new Date)
					.getTime();

			return function() {
				while ((new Date).getTime() > nextGameTick) {
					nextGameTick += skipTicks;
				}
				Game.draw();
				if (Game.nextFrame != null) {
					Game.nextFrame();
				}
			};
		})();

		Game.connect = (function() {
			Game.socket = new SockJS("/snake");

			Game.socket.onopen = function() {
				// Socket open.. start the game loop.
				Console.log('Info: WebSocket connection opened.');
				Console.log('Info: Press an arrow key to begin.');
				Game.startGameLoop();
				setInterval(function() {
					// Prevent server read timeout.
					Game.socket.send('ping');
				}, 5000);
			};

			Game.socket.onclose = function() {
				Console.log('Info: WebSocket closed.');
				Game.stopGameLoop();
			};

			Game.socket.onmessage = function(message) {
				// _Potential_ security hole, consider using json lib to parse data in production.
				var packet = eval('(' + message.data + ')');
				switch (packet.type) {
				case 'update':
					for (var i = 0; i < packet.data.length; i++) {
						Game
								.updateSnake(packet.data[i].id,
										packet.data[i].body);
					}
					break;
				case 'join':
					for (var j = 0; j < packet.data.length; j++) {
						Game.addSnake(packet.data[j].id, packet.data[j].color);
					}
					break;
				case 'leave':
					Game.removeSnake(packet.id);
					break;
				case 'dead':
					Console.log('Info: Your snake is dead, bad luck!');
					Game.direction = 'none';
					break;
				case 'kill':
					Console.log('Info: Head shot!');
					break;
				}
			};
		});

		var Console = {};

		Console.log = (function(message) {
			var console = document.getElementById('console');
			var p = document.createElement('p');
			p.style.wordWrap = 'break-word';
			p.innerHTML = message;
			console.appendChild(p);
			while (console.childNodes.length > 25) {
				console.removeChild(console.firstChild);
			}
			console.scrollTop = console.scrollHeight;
		});

		Game.initialize();
	</script>
</body>
</html>
